A light-sensitive image forming material has a layer comprising a light-sensitive resin which is capable of forming an image by imagewise exposure. The light-sensitive resin comes to be soluble or insoluble in a solvent accompanying to its molecular structure change caused by exposure of light. The formation of an image is performed by taking advantage of an above phenomenon of the light-sensitive resin. The light-sensitive image forming material have such light-sensitive resin is utilized in the fields of printing plates such as a PS (Presensitized) lithograph and a resin relief plate, photoresists such as a film type photoresist, color proofs in prepress, and lith-films for dot to dot work.
For example, a light-sensitive image forming material employable for a proof to confirm hue and tone of a finished print has a structure comprising a support (may be referred to as tentative support hereinafter) and a light-sensitive resin layer containing a pigment provided thereon or a structure comprising a support and both a colorant layer containing a pigment and a light-sensitive resin layer provided thereon in order. If necessary, a peel layer comprising an organic polymer, or the peel layer and a barrier layer comprising an organic polymer is provided on the support.
In the case of using the above light-sensitive image forming material for an image forming material (light-sensitive transferring sheet) in the surprint method (which is one of color proofing methods), the material is image-wise exposed to light to form an image on the support or the peel layer through developing and then the resultant separation image is transferred to a desired support to prepare a color proofing sheet having the separation image.
Such color proofing sheet is used to confirm hue and tone of a finished print as mentioned above, so that a separation image formed on a light-sensitive image forming material is desired to show a distinct hue.
To form a color image on a light-sensitive image forming material, a colorant material in the light-sensitive resin layer generally uses an organic pigment which is excellent in various characteristics such as sharpness, concentration (coloring power) and richness of hue. In more detail, a color image is obtained by applying a coating solution prepared through mixing the organic pigment and a light-sensitive resin to a support or a peel layer provided on a support to prepare a light-sensitive image forming material, and imagewise exposing the material to light and then removing a soluble portion of the resin layer by developing by the use of a developing solution.
It is deemed that developing solution used in the developing procedure plays an important role in whether a color image showing excellent characteristics mentioned above can be obtained or not. As a developing solution, for example, Japanese Provisional Patent Publication Nos. 62 (1987)-67529 and 63(1988)-74052 disclose an alkaline developing solution containing butyl cellosolve. Further, Japanese Provisional Patent Publication Nos. 1 (1989)-82543 and 3 (1991)-198046 disclose an alkaline developing solution containing a surface active agent, which is a mixture of plural compounds represented by the following formula: ##STR2## and is available from Kao Atlas Co., Ltd. as a trade name of Perex NBL.
The addition of the surface active agent or butyl cellosolve to the developing solution is effective to improve wetting properties for the light-sensitive resin layer and therefore occasionally shorten developing time.
The study of the present inventors, however, have revealed that even use of the developing solution containing the surface active agent and the like can not bring about the formation of an image having excellent characteristics (sharpness, coloring power and richness of hue) in a reduced developing time In more detail, use of the developing solution is apt to bring about occurrence of fog of a coloring material on the support or the peel layer and the occurrence of fog is not sufficiently prevented even if the developing time is prolonged.